SOLID-STATE MAGIC-ANGLE-SPINNING C-13 AND P-31 NMR OF ORGANIC LIGAND STABILIZED HIGH-NUCLEARITY METAL-CLUSTERS - C-13 AND P-31 MAS ON METALCLUSTER COMPOUNDS

C-13 and P-31 Solid state NMR measurements on the organic ligands in l igated Au55, Ni8, Pt309, Cu36 and Cu70 clusters are reported. The liga nds behave like diamagnetic organic molecules, giving rise to relative ly narrow lines with excellent cross-polarization efficiency. The reso nance lines of the nuclei directly bound to the metal core are systema tically broadened in the conducting compounds. No pronounced Knight sh ifts or evidence of metallic-like relaxation were observed. These resu lts support a model for the electrical conduction involving tunneling between metal cores with the ligands playing the role of a tunneling b arrier.